1. Field of the Invention
The present invention relates to treatment of avians. In another aspect, the present invention relates to the use of L-arginine for the treatment of avians. In even another aspect, the present invention relates to the administration of L-arginine to avians through drinking water for the treatment of or prevention of pulmonary hypertension syndrome, also commonly known as ascites in poultry.
2. Description of the Related Art
Pulmonary hypertension syndrome was reported as early as 1968, and is a condition characterized by mortality with the accumulation of fluid (ascites fluid) in the abdomen of the bird. Ascites fluid accumulation in the body cavity may also be caused by tumor growth in the abdominal cavity. Pulmonary hypertension syndrome is caused by a high resistance to blood flow through the lungs. This excessive resistance of blood flow through the lungs causes an adverse effect on the heart, and hence pulmonary hypertension syndrome. As used hereinafter, "ascites" and "pulmonary hypertension syndrome" will be used interchangeably with the understanding that this form of ascites in poultry is in no way related to tumor growth.
Pulmonary hypertension syndrome poses a serious problem to young fast growing poultry all over the world. First associated with flocks raised at high altitude, it is now recognized that other factors, such as cold temperatures, rapid growth, respiratory distress, high salt intake, and poor ventilation, also encourage pulmonary hypertension syndrome. Death from pulmonary hypertension syndrome results due to an enlarged heart, specifically including dilation and hypertrophy of the right ventricle. Congestive heart failure develops leading to liver damage, and kidney lung and intestinal problems, and compression of the air sac with abdominal fluids. While traditionally, male birds were at greater risk than females because of their faster growth rate, the conditions of modern poultry farming have caused female birds to suffer almost equally.
Pulmonary hypertension syndrome was originally confined to countries such as Bolivia, Columbia, Mexico, Peru, and South Africa, where poultry are traditionally raised at high altitude. It has now been reported in virtually all countries with intensive poultry production practice using modern broiler strains.
The commercial impact of pulmonary hypertension syndrome can be devastating. In fact, mortality among some United States poultry flocks can commonly amount to 5% of birds "started", and in some cases can range to over 30% of birds started. This results in millions of dollars lost due to ascites.
It has been reported that there has been a marked increase in the incidence of pulmonary hypertension syndrome in low altitude countries such as the United Kingdom, Italy, Germany, Australia and Mauritius. It has also been reported that recent evidence tends to show that ascites is now increasing during warmer weather and is now appearing at a younger age in poultry.
U.S. Pat. No. 5,217,997, issued Jun. 8, 1993 to Levere et al. discloses the use of L-arginine or a pharmaceutically acceptable salt thereof in the treatment of hypertension, bronchial asthma, and high vascular disorders in mammals. Such high vascular resistance disorders in mammals include primary or secondary vasospasm, angina pectoris, cerebral ischemia and preeclampsia of pregnancy. As disclosed, about 1 mg to about 1500 mg per day of the L-arginine or a pharmaceutically acceptable salt thereof is administered to the mammal.
U.S. Pat. No. 5,158,883, issued Oct. 27, 1992 to Griffith, discloses a method of treating mammal cells using amino arginine to block nitric oxide formation in-vitro. Typical dosages are administered in a nitric oxide synthesis inhibiting amount, generally in the range of about 10 .mu.g/kg to 100 mg/kg.
U.S. Pat. No. 5,213,815, issued May 25, 1983 to O'Brien, discloses a method of treating and preventing ascites in poultry by administering a combination of Eyebright herb and Brewer's yeast to poultry. Prevention of ascites is accomplished by adding Brewer's yeast to poultry food at a rate of about 40 grams per 160 pounds of poultry, starting from "day old" and continuing through the last day of "grow out". Treatment of ascites is accomplished by supplementing the Brewer's yeast with Eyebright herb at a rate of 500 mg per 160 pounds poultry per day for seven days.
"Dietary Arginine Influences Rous Sarcoma Growth in a Major Histocompatibility B Complex Progressor Genotype", Taylor et al., Society for Experimental Biology and Medicine, 1992, at 38-41, discloses administering five week-old chickens feed having either 0.92% or 2.40% L-arginine content to lower tumor growth. While the article reports lower tumor growth from feed high in L-arginine, it discloses that mortality was not significantly different between a low and high L-arginine diet. Additionally, this article is silent regarding treatment of chickens having pulmonary hypertension syndrome, is silent regarding administration of L-arginine prior to five weeks after hatching.
The "Nutrient Requirements of Poultry", by the Subcommittee on Poultry Nutrition, Committee on Animal Nutrition, Board of Agriculture, National Research Council, 9th Ed., 1994, at 27-42, recommends providing broilers with feed having 1 to 1.25 wt % arginine, turkeys with feed having 0.5 to 1.6 wt % arginine, and ducks feed having from 1 to 1.1 wt % arginine.
However, in spite of these advancements in the prior art, none of these prior art references disclose or suggest the administration of L-arginine to avians for the treatment and/or prevention of pulmonary hypertension syndrome.
Thus, there is still a need for a method of treating and/or preventing pulmonary hypertension syndrome in avians.
These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.